Eudorella breviflagella, Akiyama, Tadashi & Gamô, Sigeo, 2012

Akiyama, Tadashi & Gamô, Sigeo, 2012, The cumacean Genus Eudorella (Crustacea: Peracarida) from Japanese Waters, Northwest Pacific, and E. suluensis sp. nov. from the Sulu Sea, Indo-West Pacific, Zootaxa 3319, pp. 1-56 : 19-23

Eudorella breviflagella sp. nov.

( Figs. 13 , 14 )

Material examined. Holotype, ovigerous female, 2.06 mm (NSMT-Cr 22120), Enshu Nada, southern coast of Honshu, 34°33N, 138°03ˏE – 34°32N, 138°03ˏE, 240–260 m (KT-02-5, St. EN-2-3), 26 May, 2002. Paratypes; 1 ovigerous female (pleon lost), 4 preparatory females, 1.92–2.16 mm (2 specimens dissected) (NSMT-Cr 22121), (KT-02-5, St. EN-2-3); 1 adult male, 2.07 mm, dissected (NSMT-Cr 22122), Enshu Nada, 34°36ˏN, 137°59ˏE, 116–155m (KT-02-5, St. EN-4-2) 27 May, 2002; 5 ovigerous females, 1.97–2.30 mm, 8 preparatory females, 1.84–2.16 mm (3 specimens dissected), 2 adult males, 1.97–2.05 mm (NSMT-Cr 22123), Enshu Nada, 34°35ˏN, 137°59ˏE, 136–194 m (KT-04-6, St. EN-2), 2 May, 2004.

Description. Females ( Fig. 13 A, B). Body with few hairs. Carapace ( Fig. 13 C) with a few long simple setae on each side (arrow heads), length 0.20–0.21 times total body length, 1.1–1.2 times width and 1.1–1.20 times depth; upper front corner with a bundle of setae projecting upward; anterior margin not serrated; antennal notch shallow, with 0 and 2–4 large teeth on upper and lower end respectively; anterolateral angle with a tooth directed upward succeeded by 7–9 teeth on inferior margin. Pereon length 1.1–1.3 times length of carapace. Pleon 0.54– 0.57 times total body length; dorso-posterior end of 5th segment with no long setae.

Antenna 1 ( Fig. 13 D) 3rd article of peduncle shorter than 2nd, with 2 plumose setae and 1 simple seta on outer margin and with 3–4 plumose setae on inner margin; 1st article of peduncle with 0–1 and 2 plumose setae on lower and inner margins, respectively. Main flagellum subequal to or slightly longer than, 2nd joint of peduncle, with 1– 2 simple setae on outer margin of 1st joint; accessory flagellum slightly longer than 1st article of main flagellum. Antenna 2 ( Fig. 13 E) with no plumose setae on lower margin. Mandibles, maxilla 1 and maxilla 2 are normal ( Fig. 13 F–H.). Maxilliped 1 ( Fig. 13 I) with 3 branchial lobules. Maxilliped 2 ( Fig. 13 J) basis as long as following 3 articles, with a few setae on distal end and with no setae on inner margin or ventral surface. Maxilliped 3 ( Fig. 13 K) basis length 0.9–1.1 times distal articles combined, with 5–9 and 1–4 plumose setae on inner and ventral surface, respectively; carpus with 5 plumose setae on inner margin.

Pereopod 1 ( Fig. 13 L) basis length 0.6–0.7 times that of distal articles combined, with 5–7 and 2–7 setae on inner and outer margins, respectively; propodus 1.2–1.4 times carpus and 1.6–1.8 times dactylus. Pereopod 2 ( Fig. 13 M), basis 0.7–0.8 times distal articles combined; carpus 0.8–1.0 times merus; propodus half as long as merus, with deep notch on distal corner, for nearly entire length of article; dactylus not swollen distally, with 8–9 stiff setae on lateral margin and apical end. Pereopod 3 ( Fig. 13 N) basis length 1.04–1.3 times distal articles together. Pereopod 4 ( Fig. 13 O), basis 0.7–1.0 times distal articles together. Pereopod 5 ( Fig. 13 P) basis 0.5–0.7 times distal articles together.

Uropod ( Fig. 13 Q), peduncle length 1.3–1.4 times pleonite 6, 0.73–0.88 times exopod, and 1.10–1.22 times 1st article of endopod, with 3–4 setae on inner margin; exopod 1.34–1.48 times 1st article of endopod, with 6–7 simple setae on inner margin and apical end, with 2–3 simple setae on dorsal surface, and with 2–4 setae on ventral surface. Endopod 1st article 1.9–2.3 times 2nd, with 4–5 spiniform setae and 1 simple seta on inner and outer margins, respectively; 2nd article with 2–3 spiniform setae on inner margin; robust terminal seta defined at base.

Adult male ( Fig. 14 ). Carapace length 0.20 times total body length, 1.6 times the greatest width and 1.2 times depth; antennal notch absent; antero-lateral angle with a tooth projecting upward, succeeded by 8 teeth on inferior margin ( Fig. 14 C); each side of carapace without long setae. Pereon length 1.3 times that of carapace. Pleon 0.54 times total body length; dorso-posterior end of pleonite 5 with no long seta; posterior margin of pleonite 6 semicircular, not extending posteriorly.

Antenna 1 ( Fig. 14 D) stout; 3rd article of peduncle much shorter than 2nd, with 2 and 3 plumose setae on outer and inner margins, respectively; 4-articulate main flagellum longer than 2nd article of peduncle, with about 12 aesthetascs at frontal margin of basal article; 2nd article with 2 simple setae; accessory flagellum longer than combined length of 1st and 2nd articles of main flagellum. Antenna 2 ( Fig. 14 E, F) with 4 plumose setae on peduncle; flagellum short, reaching between anterior and posterior end of 4th pereonite; numerous setae on flagellum and distal 2 articles of peduncle swollen distally. Maxilliped 3 ( Fig. 14 G) basis length 1.3 times that of distal articles combined, with 5 and 4 plumose setae on inner margin and ventral surface, respectively.

Pereopod 1 ( Fig. 14 H) basis length 1.0 times that of distal articles combined, with 7 plumose setae each on inner and outer margins; propodus 1.1 times carpus and 1.8 times dactylus. Pereopod 2 ( Fig. 14 I) basis 1.2 times distal articles combined; carpus 0.8 times merus and 0.6 times combined length of propodus and dactylus; propodus with deep notch on distal corner; dactylus with 8 stiff setae projecting radially. Pereopods 3–5 ( Fig. 14 J–L) bases 2.3, 1.2, 0.8 times distal articles combined, respectively. Pleopod 1 (Fig, 14M) outer ramus absent, replaced by 2 stiff simple setae.

Uropod ( Fig. 14 N) peduncle with 4 setae on inner margin, length 1.3 times as long as pleonite 6, 0.86 times exopod and 1.17 times 1st article of endopod. Exopod length 1.36 times as long as 1st article of endopod, with 6 setae on inner margin and apical end, 3 setae on dorsal surface and a seta on ventral surface. Endopod 1st article 2.1 times the 2nd article, with 7 setae on inner margin; 2nd article with 3 spiniform setae on inner margin.

Etymology. The species name refers to the short flagellum of antenna 2 in adult males.

Remarks. The present new species is closely allied to Eudorella orientalis sp. nov. from Japan. The females of E. breviflagella sp. nov. are distinguished from the latter only as follows. (1) The basis of the pereopods 3–5 are short, 1.1–1.3, 0.7–1.0, 0.5–0.7 times the combined length of the distal articles together (1.4–2.2, 1.1–1.9, 1.1–1.5 times in E. orientalis ). (2) The basal article of the uropod endopod has 4–5 spiniform setae (6–9 setae in E. orientalis ). (3) The body size is very small (1.8–2.3 mm, cf. 2.9–4.8 mm in E. orientalis ). Adult males of E. breviflagella are clearly separated from E. orientalis by the following characters. (1) The inferior margin of the carapace is serrated with eight teeth (1–2 teeth in E. orientalis ). (2) The hind margin of the last pleonite is semicircular, and not elongated posteriorly (vs. triangular, and exceeding the anal opening in E. orientalis ). (3) The flagellum of the antenna 2 is short, not reaching the posterior end of pereonite 4 (reaching the posterior end of the pleon in E. orientalis ). (4) The pleopod outer ramus is absent, replaced by two simple setae (present in E. orientalis ). Eudorella breviflagella is currently the smallest in the genus.

Distribution. Enshu Nada, pacific coast of southern Honshu Island, 116– 260 m.

Figures

FIGURE 13. Eudorella breviflagella sp. nov., A, Q, holotype ovigerous female; B – P, paratype preparatory female. A, body, lateral view; B, anterior portion of body, from above; C, carapace; D, antenna 1; E, antenna 2; F, mandibles; G, maxilla 1; H, maxilla 2; I – K, maxillipeds 1 – 3; L – P, pereopods 1 – 5, Q, uropod with pleonite 6.

FIGURE 14. Eudorella breviflagella sp. nov., adult male. A, body, lateral view; B, anterior portion of body, from above; C, anterior portion of carapace; D, antenna 1; E, F, antenna 2; G, maxilliped 3; H – L, pereopods 1 – 5, M, pleopod 1; N, uropod with pleonite 6.